Modulated drug delivery refers to matching the release profiles of drugs to the physiological requirements of the patient. This type of controlled delivery is useful for treating diseases that affect the homeostatic functions of the body, such as diabetes mellitus. Insulin therapy for diabetes requires a low baseline release of the drug, with peaks after the ingestion of food.
Various methods of accomplishing modulated in vivo drug delivery have been described in the literature. Mechanical pumps are one type of device that is commonly employed. Another method that has been examined is the use of ultrasound to rupture microcapsules or strip a layer of material from a drug-containing polymer matrix to alter drug release. Potential problems with such ultrasound techniques include concurrent rupture of cells at high levels of insonation power and concern about the long term safety of repetitive exposure of body tissues to ultrasonic energy.
Certain temperature sensitive hydrophilic polymer gels (hydrogels) have been described as another means of modulating drug delivery. When the temperature of the polymer is raised above its lower critical solution temperature (LCST), the hydrogel undergoes a reversible phase transition that results in the collapse of the hydrogel structure. The hydrogel collapse forces soluble materials held within the hydrogel matrix to be expelled into the surrounding solution. An impediment to the development of temperature-sensitive materials into clinically useful modulated drug delivery devices has been the lack of satisfactory means for altering the temperature of the implanted device.
Safe and efficient alternative compositions and methods for triggered drug release are provided herein. In addition, on-demand, adaptive drug delivery systems and methods are provided, including triggered drug release.